Field of the Invention
The present invention relates to an imaging apparatus configured to acquire an optical coherence tomographic image, a method of operating the imaging apparatus, an information processing apparatus to be connected to the imaging apparatus, and a storing medium.
Description of the Related Art
An imaging apparatus employing optical coherence tomography which is hereinafter referred to as OCT and the imaging apparatus employing OCT which is hereinafter referred to as “OCT unit” has been developed (Japanese Patent Application Laid-Open No. 2012-115578). In the OCT unit, light is irradiated on an object while changing a wavelength of the irradiation light to cause interference between reflected light, which is obtained as the irradiation light returning from different depths of the object, and reference light corresponding to the irradiation light. Then, frequency components included in a time waveform of the strength of the coherent light (hereinafter abbreviated as “interference spectrum”) is analyzed to obtain information on a section of the object, and more specifically, a tomographic image. Such an OCT unit is used in fundus inspection, for example.
Many ocular diseases are difficult to be completely cured, and hence it is important to discover a lesion of the fundus at an early stage, and to start treatment to delay the progress of the lesion extending over a wide area of the fundus at an early stage. In particular, a profound effect is exerted on a visual sense when the lesion reaches a macula, and hence there is a demand that the lesion be discovered even when the lesion exists at a position sufficiently distant from the macula. In order to satisfy the demand, the OCT apparatus used for the fundus inspection is expected to have a wider field angle.
As a technology to satisfy such expectation, in Japanese Patent Application Laid-Open No. 2012-115578, to widen an observation area of a tomographic image of a fundus, connecting a plurality of tomographic images to one another to form a tomographic image of a wide range is disclosed. In Japanese Patent Application Laid-Open No. 2012-115578, an OCT unit employing a variable wavelength light source (swept source OCT unit, hereinafter referred to as “SS-OCT unit”) is also disclosed, and as the variable wavelength light source, a fiber ring resonator and a wavelength selective filter are exemplified.
However, in the method disclosed in Japanese Patent Application Laid-Open No. 2012-115578, image processing for sequentially connecting the acquired plurality of tomographic images is time-consuming and troublesome. Therefore, it is preferred to acquire the information on the section over the wide range in one image acquisition cycle. In this case, an eyeball is substantially spherical, and hence optical path lengths of the irradiation light significantly vary for a central portion and a peripheral portion of the fundus. Therefore, with the OCT unit having the structure of the related art, the information on the section cannot be obtained accurately over the wide range in some cases.